The present invention claims a priority based on the Japanese Patent Application No. H10-328007, the contents of which is incorporated hereinto by reference in its entirety.
1. Field of the Invention
This invention relates to an interchangeable image taking lens for use in a camera such as a digital camera, a silver halide camera and a video camera.
2. Description of the Related Art
A digital camera equipped with an interchangeable image taking lens unit is known. As an interchangeable image taking lens for a digital camera, an existing interchangeable lens for a silver halide camera is normally used. In this specification, for the sake of convenience, a camera for taking an image by a silver halide film is referred to as a silver halide camera.
However, a digital camera is different from a silver halide camera in a focus detection system for an automatic focusing (hereinafter referred to as xe2x80x9cAZxe2x80x9d) control and a photometry system for an automatic exposure (hereinafter referred to as xe2x80x9cAExe2x80x9d) control.
In addition, although a digital camera employs a contrast detection system among TTL systems (Through The Lens systems), a silver halide camera usually employs a phase difference detecting system equipped with line sensors. The aforementioned contrast detection system employed by a digital camera is quite different from the phase difference detecting system employed by a silver halide camera in characteristic. Furthermore, a digital camera is required to deal with a moving image taking which is not required by a silver halide camera.
Therefore, with respect to an actuator for driving a lens unit and/or parts of a taking lens such as an aperture diaphragm, a digital camera requires operation characteristics different from that required by a silver halide camera. As a result, it was practically difficult to take an image at optimum conditions by a digital camera with an interchangeable lens designed for a silver halide camera.
To solve the aforementioned drawbacks, it may be considered to select either an interchangeable lens equipped with an actuator suitable for a digital camera or an interchangeable lens equipped with an actuator suitable for a silver halide camera depending on the camera to be used. However, this requires two kinds of interchangeable lenses, one of which being suitable for a digital camera and the other for a silver halide camera, resulting in inconvenience and uneconomical.
Therefore, it is an object of the present invention to provide an interchangeable lens which can perform suitable operation for a plurality of camera bodies, and which can be easily handled by a user and can reduce economical expenses of the user.
It is another object of the present invention to provide an interchangeable lens which can perform at optimum operating conditions for a plurality of different types of camera bodies such as a digital camera body and a silver halide camera body.
According to one aspect of the present invention, a lens to be interchangeably attached to a camera body includes a first actuator which is appropriately used for a first camera body to which the interchangeable lens is to be attached, and a second actuator which is appropriately used for a second camera body to which the interchangeable lens is to be attached.
With this interchangeable lens, it is possible to operate the appropriate first or second actuator depending on the first or second camera body to which the interchangeable lens is to be attached. Therefore, a single interchangeable lens can be performed at optimum operating conditions for a camera body to which the interchangeable lens is to be attached. For example, even if the interchangeable lens is selectively attached to one of the different types of digital cameras, it is possible to take an image at optimum conditions depending on the type of digital camera and the like.
According to another aspect of the present invention, a lens to be interchangeably attached to one of a plurality of different types of camera bodies includes a first actuator which is appropriately used for a first type of the camera body to which the interchangeable lens is to be attached, and a second actuator which is appropriately used for a second type of the camera body t o which the interchangeable lens is to be attached.
With this interchangeable lens, it is possible to operate an appropriate first or second actuator depending on the first or second camera body different in type. Therefore, a single interchangeable lens can be used at optimum operating conditions for both digital and silver halide camera bodies.
It is preferable that the interchangeable lens further includes a first electric contact to which an electric contact of the first camera body is to be electrically connected, and a second electric contact to which an electric contact of the second camera body is to be electrically connected, whereby the first or second actuator to be activated is selected depending on which of the first and second electric contacts is electrically connected to the electric contact of the first or second camera body.
According to this structure, since an actuator appropriate to the first or second type of the camera body is automatically selected by simply attaching the interchangeable lens to the first or second type of the camera body, the operability can be improved.
It is also preferable that the interchangeable lens further includes a switching mechanism for switching a first connected state in which the first actuator is connected to a driving member to be driven to a second connected state in which the second actuator is connected to the driving member, and vice versa.
If the first and second actuators are always connected to the driving member, when the selected actuator drives the driving member, the driving member reversely drives the non-selected actuator. Therefore, the selected actuator is required to have large driving force. However, by switching the connection of the driving member and the first or second first actuator depending on the type of the camera body, such an inconvenience that the driving member reversely drives the non-selected actuator is canceled. As a result, each actuator is not required to have large driving power.